1. Technical Field
This application relates to chemical analysis and more particularly to systems and methods that use the Nuclear Quadrupole Resonance effect to determine the identity of a substance.
2. Background
As described in the above-referenced co-pending patent applications, a system that uses the Nuclear Quadrupole Resonance (NQR) effect for detecting a substance typically uses one or more conductive surfaces to define an area, or portal, that is to be monitored. Two or more conductors, typically thin wires, are disposed within the portal adjacent the conductive surfaces. The wires are each individually electrically terminated; alternatively, they can be arranged as balanced transmission lines. The wires are driven with a Radio Frequency (RF) transmitter that generates one or more continuously varying radio frequency modulated chirp signals. The wires then radiate electromagnetic energy into the portal.
The resulting time varying electromagnetic fields then stimulate Nuclear Quadrupole Resonance in any material with an electric quadrupole moment located within the portal to cause the material(s) to emit coherent Radio Frequency (RF) emissions. These coherent RF emissions are then detected and further processed to determine characteristics of the substance, such as by detecting their amplitude, phase and/or frequency.